Hi Trevor I have a 2006 X Type 2.0L diesel with 60K miles on the clock. About 2 years ago the glowplug warning light came on then reset after stopping the engine and starting it again but it kept coming back and when it was on the engine performance was restricted. no fault codes showed up. I removed the EGR valve and found it about 50% blocked with carbon/soot, I replaced the valve and blanked it off with the plate without the hole ( about £6 on Ebay) So far so good, 2 years later it hasn't come back and fuel consumption has improved by about 4MPG. Hope this helps. Pete